Re: Streaming of WebVTT

On Wed, Jul 25, 2012 at 9:18 AM, Cyril Concolato <
cyril.concolato@telecom-paristech.fr> wrote:

> I'm trying to integrate WebVTT content in streaming context (MP4, RTP,
> DASH, MPEG-2 ...) in general. Aside from the problem of random access
> points that I mentionned in my previous email [1], there is a problem with
> the fact that the "WEBVTT" string has to be at the beginning of the file.
> Consider the following case, I have a live event and I want client to
> connect to an HTTP-delivered WebVTT resource, I'd like to update that
> resource from time to time (removing old cues, adjusting times and adding
> new cues) and enable both clients already connected to get the update and
> for new clients to get the new content. That same file has to have the
> "WEBVTT" string for new clients, but cannot be used as is for the already
> connected client (I'll have to strip off the "WEBVTT" string). What is the
> use of that string? Is it really needed given that many resources on the
> web don't use magic numbers (HTML, XML, SRT, SVG, ...)?
>

You'll need the ability to deal with "header" data anyway.  There have been
proposals for adding headers for metadata, default cue settings, inline
CSS, and so on.  It may be a while if any of them are implemented, but
please try to avoid designing a system that expects WebVTT to be a
headerless format.

-- 
Glenn Maynard